# How come fault lines don't swallow up the oceans? **URL:** \ **Category:** Factual Questions\ **Created:** [May 24, 2006, 10:12pm UTC](https://boards.straightdope.com/t/how-come-fault-lines-dont-swallow-up-the-oceans/358096 "2006-05-24T22:12:08Z")\ **Posts on this page:** 12\ **Page:** 1
**Author:** ![balloonman](https://avatars.discourse-cdn.com/v4/letter/b/47e85d/32.png) [@balloonman](https://boards.straightdope.com/u/balloonman)\ **Post date:** [May 24, 2006, 10:12pm UTC](https://boards.straightdope.com/t/how-come-fault-lines-dont-swallow-up-the-oceans/358096/1 "2006-05-24T22:12:08Z")
i’ve always been curious about this. since the earth’s crust is made up of huge plates that have many cracks and slide under each other into the mantle, why doesn’t something like a huge fault line or underwater volcano suck huge areas of ocean down beneath the crust? ---
**Author:** ![Bobotheoptimist](https://avatars.discourse-cdn.com/v4/letter/b/919ad9/32.png) [@Bobotheoptimist](https://boards.straightdope.com/u/Bobotheoptimist)\ **Post date:** [May 24, 2006, 10:18pm UTC](https://boards.straightdope.com/t/how-come-fault-lines-dont-swallow-up-the-oceans/358096/2 "2006-05-24T22:18:14Z")
> [@balloonman](#): > > i’ve always been curious about this. since the earth’s crust is made up of huge plates that have many cracks and slide under each other into the mantle, why doesn’t something like a huge fault line or underwater volcano suck huge areas of ocean down beneath the crust? The planet is a big ol’ ball of rock covered iron, and since rock is heavier than water the Earth sinks under the oceans not the other way around. ---
**Author:** ![Lemur866](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/lemur866/32/434_2.png) [@Lemur866](https://boards.straightdope.com/u/Lemur866)\ **Post date:** [May 24, 2006, 10:21pm UTC](https://boards.straightdope.com/t/how-come-fault-lines-dont-swallow-up-the-oceans/358096/3 "2006-05-24T22:21:41Z")
Water is lighter than rock. Also, superheated steam is lighter than rock. This is why rocks sink when thrown into water, while water thrown onto rock floats. Also, paper covers rock, but water smooshes paper. ---
**Author:** ![wevets](https://avatars.discourse-cdn.com/v4/letter/w/e9a140/32.png) [@wevets](https://boards.straightdope.com/u/wevets)\ **Post date:** [May 24, 2006, 10:23pm UTC](https://boards.straightdope.com/t/how-come-fault-lines-dont-swallow-up-the-oceans/358096/4 "2006-05-24T22:23:19Z")
Water does seep down into cracks in the Earth’s crust, but as it approaches the magma and hot regions of the lithosphere, it heats up, which will force the expanding and superheated water to rise, and then it comes out of [hydrothermal vents](http://life.bio.sunysb.edu/marinebio/hotvent.html). So water does find its way down, but the Earth is not empty, so there’s really nowhere for all that water to go, then because of the temperature difference, it comes back up. ---
**Author:** ![balloonman](https://avatars.discourse-cdn.com/v4/letter/b/47e85d/32.png) [@balloonman](https://boards.straightdope.com/u/balloonman)\ **Post date:** [May 24, 2006, 10:30pm UTC](https://boards.straightdope.com/t/how-come-fault-lines-dont-swallow-up-the-oceans/358096/5 "2006-05-24T22:30:37Z")
ahhh. i feel smarter now… thanks! ---
**Author:** ![BrainGlutton](https://avatars.discourse-cdn.com/v4/letter/b/82dd89/32.png) [@BrainGlutton](https://boards.straightdope.com/u/BrainGlutton)\ **Post date:** [May 24, 2006, 10:57pm UTC](https://boards.straightdope.com/t/how-come-fault-lines-dont-swallow-up-the-oceans/358096/6 "2006-05-24T22:57:28Z")
> [@wevets](#): > > So water does find its way down, but the Earth is not empty . . . Heretic! [http://en.wikipedia.org/wiki/Hollow\_earth](http://en.wikipedia.org/wiki/Hollow_earth) ---
**Author:** ![Ludovic](https://avatars.discourse-cdn.com/v4/letter/l/7ab992/32.png) [@Ludovic](https://boards.straightdope.com/u/Ludovic)\ **Post date:** [May 24, 2006, 11:33pm UTC](https://boards.straightdope.com/t/how-come-fault-lines-dont-swallow-up-the-oceans/358096/7 "2006-05-24T23:33:38Z")
What about really tiny rocks? ---
**Author:** ![Inigo\_Montoya](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/inigo_montoya/32/124_2.png) [@Inigo\_Montoya](https://boards.straightdope.com/u/Inigo_Montoya)\ **Post date:** [May 24, 2006, 11:35pm UTC](https://boards.straightdope.com/t/how-come-fault-lines-dont-swallow-up-the-oceans/358096/8 "2006-05-24T23:35:36Z")
> [@Lemur866](#): > > Water is lighter than rock. Also, superheated steam is lighter than rock. > > This is why rocks sink when thrown into water, while water thrown onto rock floats. > > Also, paper covers rock, but water smooshes paper. But nothing beats [TIGER HAND!!!](http://www.rockpapersaddam.com/one.html) ---
**Author:** ![Bobotheoptimist](https://avatars.discourse-cdn.com/v4/letter/b/919ad9/32.png) [@Bobotheoptimist](https://boards.straightdope.com/u/Bobotheoptimist)\ **Post date:** [May 25, 2006, 4:37am UTC](https://boards.straightdope.com/t/how-come-fault-lines-dont-swallow-up-the-oceans/358096/9 "2006-05-25T04:37:08Z")
> [@Ludovic](#): > > What about really tiny rocks? CHURCHES! Churches… I really hope Ludovic was making a Monty Python reference, otherwise the “churches” crack doesn’t make a lick of sense ---
**Author:** ![wevets](https://avatars.discourse-cdn.com/v4/letter/w/e9a140/32.png) [@wevets](https://boards.straightdope.com/u/wevets)\ **Post date:** [May 25, 2006, 3:30pm UTC](https://boards.straightdope.com/t/how-come-fault-lines-dont-swallow-up-the-oceans/358096/10 "2006-05-25T15:30:32Z")
> [@BrainGlutton](#): > > Heretic! > > [http://en.wikipedia.org/wiki/Hollow\_earth](http://en.wikipedia.org/wiki/Hollow_earth) No, No, I truly BELEIVE, don’t forget to take into account the [water canopy theory](http://www.absoluteastronomy.com/enc1/vapor_canopy)… but the TRUTH is we’re living on top of the canopy!!! 😉 ---
**Author:** ![UncleBeer](https://avatars.discourse-cdn.com/v4/letter/u/977dab/32.png) [@UncleBeer](https://boards.straightdope.com/u/UncleBeer)\ **Post date:** [May 25, 2006, 6:08pm UTC](https://boards.straightdope.com/t/how-come-fault-lines-dont-swallow-up-the-oceans/358096/11 "2006-05-25T18:08:26Z")
> [@Inigo Montoya](#): > > But nothing beats [TIGER HAND!!!](http://www.rockpapersaddam.com/one.html) Shit! That was hysterical. Thanks, Inigo. ---
**Author:** ![Excalibre](https://avatars.discourse-cdn.com/v4/letter/e/898d66/32.png) [@Excalibre](https://boards.straightdope.com/u/Excalibre)\ **Post date:** [May 25, 2006, 7:56pm UTC](https://boards.straightdope.com/t/how-come-fault-lines-dont-swallow-up-the-oceans/358096/12 "2006-05-25T19:56:23Z")
> [@Bobotheoptimist](#): > > CHURCHES! Churches… Lead! Lead!